The Citizens have been linked with a move for the Barcelona forward, who single-handedly led his side to the 2018 World Cup on Tuesday night.
But he would come at a staggering cost due to the £268.7million release clause written into his contract with the Catalan giants.
That said, Aguero doesn’t believe finances would be an issue for Pep Guardiola’s men, but admits the potential deal would be “complicated” for another reason.
“The money isn’t a problem here,” Aguero told TyC Sport.
“But I think Messi, like [Cristiano] Ronaldo, are players who are symbols of their clubs and it’s difficult for them to leave.
“I would love to have Leo on my team, but that seems quite complicated.”
Aguero missed Argentina’s crunch game with Ecuador on Tuesday with a broken rib sustained in a car accident in Holland.
But he watched from the sidelines as Argentina went a goal behind before Messi bagged a hat-trick to ensure his nation would be heading to Russia.